Fairchild Semiconductor's FAN6920MR, an integrated, critical mode PFC and quasi-resonant current mode PWM controller, meets regulatory requirements by providing more than 90% efficiency and less than 300mW at no load for increased power savings. The device combines a PFC controller and a quasi-resonant PWM controller for what the company claims is a cost-effective design using less external components. For PFC, the device uses a controlled on-time technique to provide a regulated DC output voltage and perform natural power factor correction. With a THD (total harmonic distortion) optimiser, the device can reduce input current distortion at zero-crossing duration to improve THD performance. For PWM control, it provides many functions to improve the power system performance including extended valley detect up to the 12th valley cycle, improved light load efficiency, green-mode operation, an internal 10ms softstart and high/low line over-power compensation. It also provides various protection functions including brownout, secondary-side open-loop and over-current with auto recovery, external auto-recovery protection triggering and internal over-temperature shutdown. Available in a 16pin small outline package, the PFC/PWM controller is suitable for AIO computers, AC/DC netbook adapters (Slim Pack), open-frame SMPS and battery chargers.
